Web browsers use a variety of cookie types to enhance browsing experiences for user, content provider and advertisers alike. Among these cookies are personalization cookies that are used to remember information about the user in order to show relevant content to that user over time. For example, a web server might send a cookie containing the username last used to log into a website so that it may be filled in automatically the next time the user logs in.
Many websites use cookies for personalization based on user preferences. Then when the user accesses a page on the website, the server can personalize the page according to the user preferences. However, personalization cookies can be abused by web servers if used to construct a profile used to track user behavior. As such, there are security concerns in these and other uses of cookies.